1. Field
The present disclosure relates to a sheet feeding device used for an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction peripheral thereof, and for the image forming apparatus including the same. In particular, the present disclosure relates to the sheet feeding device including a sheet feed cassette and a manual bypass tray, and the image forming apparatus including the same.
2. Description of Related Art
In the image forming apparatus, a sheet is transported to an image forming portion. After transferring a toner image formed on an image carrier in the image forming portion onto the sheet, a process of fixing the toner image onto the sheet is performed so as to form the image. As a method of transporting the sheet to the image forming portion, there are two methods. One is a cassette feeding method in which a plurality of sheets are stacked in a sheet feed cassette in advance, and the sheets are picked up one by one from the sheet feed cassette and are sent out to the image forming portion. The other is a manual bypass feeding method in which the sheet is set onto a manual bypass tray and is sent to the image forming portion. The image forming apparatus includes both the sheet feed cassette and the manual bypass tray. Sheets of a size used frequently for printing are stacked in the sheet feed cassette, while an envelope, a special sheet such as thick paper, or a sheet of a size that is not stacked in the sheet feed cassette is set onto the manual bypass tray. Then, one of the methods is selected so that the sheet is sent out.
Usually, a cassette feed roller is used for sending out the paper from the sheet feed cassette to the image forming portion, and a manual bypass roller is used for sending out the paper from the manual bypass tray. In addition, there is known a technique of using the same feed roller for sending out both the sheet from the sheet feed cassette and the sheet from the manual bypass tray to the image forming portion.
As to the above-mentioned technique, in a sheet feeding device of a first related technique, the sheet feed cassette and the manual bypass tray are disposed in a vertically stacked manner. The feed roller is disposed on the sheet feed cassette in a pivotable manner, and an upper slide plate and a lower slide plate are disposed on the manual bypass tray in a slidable manner in a direction of sending out the sheet. In a state where the feed roller contacts with the sheet feed cassette, the sheet stacked in the sheet feed cassette can be sent out. On the other hand, when the sheet on the manual bypass tray is sent out, the upper slide plate is made to slide. Then, the lower slide plate moves to slide toward the feed roller so that the feed roller is lifted up toward the upper face of the lower slide plate. Thus, the sheet set on the manual bypass tray can be sent out by the feed roller.
However, the sheet feeding device of the first related technique needs a mechanism for driving the feed roller to rock, and it is necessary to dispose the upper slide plate and the lower slide plate sliding in the direction of sending out the sheet. Therefore, there is a disadvantage that a structure of the apparatus becomes complicated.